Features of the microstructural and mechanical degradation of long term operated mild steel

2018 ◽  
Vol 9 (3) ◽  
pp. 296-306 ◽  
Author(s):  
Halyna Krechkovska ◽  
Oleksandra Student ◽  
Grzegorz Lesiuk ◽  
José Correia
Keyword(s):  
Impact Toughness ◽  
Acid Rain ◽  
Relative Elongation ◽  
Structural Features ◽  
Mechanical Tests ◽  
Mechanical Degradation ◽  
Content Type ◽  
Hydrogenation Condition ◽  
Synthetic Acid

Purpose The purpose of this paper is to assess the technical state of old and repair steels of Shukhov’s tower elements after operation during ~ 110 and 70 years of the water tower in Nikolaev, basing on their mechanical tests, metallography and fractography investigations. Design/methodology/approach For their certification, the fractographic and structural features and mechanical properties (hardness, strength, plasticity and impact toughness) were analyzed. Both the steels under consideration were characterized by low values of hardness and brittle fracture resistance. The mechanical characteristics of the old steel are lower compared with the repair one. It cannot be only explained by the quality of metal rolling. Moreover, the plasticity characteristics of both steels, defined in synthetic acid rain environment, are lower than in the air. Using fractography investigation, the operational damages in the bulk metal in the form of the elements of cleavage fracture in the central part of the fracture surfaces of specimens tested at the hydrogenation condition by synthetic acid rain environment were revealed. Findings The results of this study suggested a degradation of steels’ characteristics caused by the development of scattering damages during their operation. Higher relative elongation of the old steel at lower hardness and impact toughness were also evidenced in that. The metallography and fractography investigations also supported this finding. Originality/value This original study aimed at characterizing the microstructural and mechanical degradation of mild steels that was collected from Shukhov’s tower structural elements.

scholarly journals Heat Treatment of Corrosion Resistant Steel for Water Propellers Fabricated by Direct Laser Deposition

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2738 ◽  
Author(s):  
Ruslan Mendagaliev ◽  
Olga Klimova-Korsmik ◽  
Vladimir Promakhov ◽  
Nikita Schulz ◽  
Alexander Zhukov ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Impact Toughness ◽  
Relative Elongation ◽  
Steel Powder ◽  
Structural Features ◽  
Laser Deposition ◽  
Initial State ◽  
Cast Material ◽  
Direct Laser Deposition ◽  
Direct Laser

The urgency of heat treatment of samples of maraging steel obtained by direct laser deposition from steel powder 06Cr15Ni4CuMo is considered. The structural features and properties of 06Cr15Ni4CuMo steel samples after direct laser deposition and heat treatment are studied. The work is devoted to research into the influence of thermal processing on the formation of structure and the mechanical properties of deposit samples. Features of formation of microstructural components by means of optical microscopy are investigated. Tests for tension and impact toughness are conducted. As a result, it was established that the material obtained by the direct laser deposition method in its initial state significantly exceeds the strength characteristics of heat treatment castings of similar chemical composition, but is inferior to it in terms of impact toughness and relative elongation. The increase in relative elongation and impact toughness up to the level of cast material in the deposit samples is achieved at the subsequent heat treatment, which leads to the formation of the structure of tempered martensite and reduction in its content at two-stage tempering in the structure of the metal. The strength of the material is also reduced to the level of cast metal.

Provenance description of metadata application profiles for long-term maintenance of metadata schemas

2018 ◽  
Vol 74 (1) ◽  
pp. 36-61 ◽  
Author(s):  
Chunqiu Li ◽  
Shigeo Sugimoto
Keyword(s):  
Structural Changes ◽  
Public Library ◽  
Structural Features ◽  
Dublin Core ◽  
Content Type ◽  
Metadata Schema ◽  
Proposed Model ◽  
Application Profile ◽  
Over Time

Purpose Provenance information is crucial for consistent maintenance of metadata schemas over time. The purpose of this paper is to propose a provenance model named DSP-PROV to keep track of structural changes of metadata schemas. Design/methodology/approach The DSP-PROV model is developed through applying the general provenance description standard PROV of the World Wide Web Consortium to the Dublin Core Application Profile. Metadata Application Profile of Digital Public Library of America is selected as a case study to apply the DSP-PROV model. Finally, this paper evaluates the proposed model by comparison between formal provenance description in DSP-PROV and semi-formal change log description in English. Findings Formal provenance description in the DSP-PROV model has advantages over semi-formal provenance description in English to keep metadata schemas consistent over time. Research limitations/implications The DSP-PROV model is applicable to keep track of the structural changes of metadata schema over time. Provenance description of other features of metadata schema such as vocabulary and encoding syntax are not covered. Originality/value This study proposes a simple model for provenance description of structural features of metadata schemas based on a few standards widely accepted on the Web and shows the advantage of the proposed model to conventional semi-formal provenance description.

Dual-isotope single-photon emission computerized tomography scanning in patients with glioblastoma multiforme: association with patient survival and histopathological characteristics of tumor after high-dose radiotherapy

1998 ◽  
Vol 89 (1) ◽  
pp. 60-68 ◽  
Author(s):  
Richard B. Schwartz ◽  
B. Leonard Holman ◽  
Joseph F. Polak ◽  
Basem M. Garada ◽  
Marc S. Schwartz ◽  
...  
Keyword(s):  
Survival Rate ◽  
Glioblastoma Multiforme ◽  
Single Photon ◽  
Photon Emission ◽  
High Dose ◽  
Term Survival ◽  
Content Type ◽  
Dual Isotope ◽  
Fine Print

Object. The study was conducted to determine the association between dual-isotope single-photon emission computerized tomography (SPECT) scanning and histopathological findings of tumor recurrence and survival in patients treated with high-dose radiotherapy for glioblastoma multiforme. Methods. Studies in which SPECT with 201Tl and 99mTc-hexamethypropyleneamine oxime (HMPAO) were used were performed 1 day before reoperation in 47 patients with glioblastoma multiforme who had previously been treated by surgery and high-dose radiotherapy. Maximum uptake of 201Tl in the lesion was expressed as a ratio to that in the contralateral scalp, and uptake of 99mTc-HMPAO was expressed as a ratio to that in the cerebellar cortex. Patients were stratified into groups based on the maximum radioisotope uptake values in their tumor beds. The significance of differences in patient gender, histological characteristics of tissue at reoperation, and SPECT uptake group with respect to 1-year survival was elucidated by using the chi-square statistic. Comparisons of patient ages and time to tumor recurrence as functions of 1-year survival were made using the t-test. Survival data at 1 year were presented according to the Kaplan—Meier method, and the significance of potential differences was evaluated using the log-rank method. The effects of different variables (tumor type, time to recurrence, and SPECT grouping) on long-term survival were evaluated using Cox proportional models that controlled for age and gender. All patients in Group I (201Tl ratio < 2 and 99mTc-HMPAO ratio < 0.5) showed radiation changes in their biopsy specimens: they had an 83.3% 1-year survival rate. Group II patients (201T1 ratio < 2 and 99mTc-HMPAO ratio of ≥ 0.5 or 201Tl ratio between 2 and 3.5 regardless of 99mTc-HMPAO ratio) had predominantly infiltrating tumor (66.6%); they had a 29.2% 1-year survival rate. Almost all of the patients in Group III (201Tl ratio > 3.5 and 99mTc-HMPAO ratio ≥ 0.5) had solid tumor (88.2%) and they had a 6.7% 1-year survival rate. Histological data were associated with 1-year survival (p < 0.01); however, SPECT grouping was more closely associated with 1-year survival (p < 0.001) and was the only variable significantly associated with long-term survival (p < 0.005). Conclusions. Dual-isotope SPECT data correlate with histopathological findings made at reoperation and with survival in patients with malignant gliomas after surgical and high-dose radiation therapy.

Long-term management of patients with multiple brain metastases after shaped beam radiosurgery

2004 ◽  
pp. 406-412
Author(s):  
Paul Okunieff ◽  
Michael C. Schell ◽  
Russell Ruo ◽  
E. Ronald Hale ◽  
Walter G. O'Dell ◽  
...  
Keyword(s):  
Brain Metastases ◽  
Tumor Control ◽  
Content Type ◽  
Negative Results ◽  
Multiple Metastases ◽  
Extracranial Disease ◽  
Successful Control ◽  
The Brain

✓ The role of radiosurgery in the treatment of patients with advanced-stage metastatic disease is currently under debate. Previous randomized studies have not consistently supported the use of radiosurgery to treat patients with numbers of brain metastases. In negative-results studies, however, intracranial tumor control was high but extracranial disease progressed; thus, patient survival was not greatly affected, although neurocognitive function was generally maintained until death. Because the future promises improved systemic (extracranial) therapy, the successful control of brain disease is that much more crucial. Thus, for selected patients with multiple metastases to the brain who remain in good neurological condition, aggressive lesion-targeting radiosurgery should be very useful. Although a major limitation to success of this therapy is the lack of control of extracranial disease in most patients, it is clear that well-designed, aggressive treatment substantially decreases the progression of brain metastases and also improves neurocognitive survival. The authors present the management and a methodology for rational treatment of a patient with breast cancer who has harbored 24 brain metastases during a 3-year period.

Spinal meningioma after treatment for Hodgkin disease

2001 ◽  
Vol 95 (2) ◽  
pp. 232-235 ◽  
Author(s):  
Andrew J. Martin ◽  
Christopher J. Hammond ◽  
H. Jane Dobbs ◽  
Safa Al-Sarraj ◽  
Nicholas W. M. Thomas
Keyword(s):  
Hodgkin Disease ◽  
Second Primary ◽  
Combined Modality Treatment ◽  
Spinal Meningioma ◽  
Primary Tumors ◽  
Content Type ◽  
Radiation Induced ◽  
Mutagenic Effects ◽  
Long Term Survivors

✓ Long-term survivors of Hodgkin disease may develop second primary tumors caused by the mutagenic effects of radio- and chemotherapy. The authors describe the case of a 35-year-old woman who presented with an unusual meningioma of the cervical spine 9 years after undergoing combined-modality treatment for Hodgkin disease. To the authors' knowledge, this is the first report of spinal meningioma as a complication of such therapy. Whereas radiation-induced intracranial meningiomas are well described in the literature, treatment-induced meningiomas of the spine have not been widely recognized.

scholarly journals Chitosan hydrogel/silk fibroin/Mg(OH)2 nanobiocomposite as a novel scaffold with antimicrobial activity and improved mechanical properties

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Reza Eivazzadeh-Keihan ◽  
Fateme Radinekiyan ◽  
Hooman Aghamirza Moghim Aliabadi ◽  
Sima Sukhtezari ◽  
Behnam Tahmasebi ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Cell Viability ◽  
Silk Fibroin ◽  
Analytical Techniques ◽  
Structural Features ◽  
Mechanical Tests ◽  
Chitosan Hydrogel ◽  
Biological Capacity ◽  
Ft Ir ◽  
Novel Scaffold

AbstractHerein, a novel nanobiocomposite scaffold based on modifying synthesized cross-linked terephthaloyl thiourea-chitosan hydrogel (CTT-CS hydrogel) substrate using the extracted silk fibroin (SF) biopolymer and prepared Mg(OH)2 nanoparticles was designed and synthesized. The biological capacity of this nanobiocomposite scaffold was evaluated by cell viability method, red blood cells hemolytic and anti-biofilm assays. According to the obtained results from 3 and 7 days, the cell viability of CTT-CS/SF/Mg(OH)2 nanobiocomposite scaffold was accompanied by a considerable increment from 62.5 to 89.6% respectively. Furthermore, its low hemolytic effect (4.5%), and as well, the high anti-biofilm activity and prevention of the P. aeruginosa biofilm formation confirmed its promising hemocompatibility and antibacterial activity. Apart from the cell viability, blood biocompatibility, and antibacterial activity of CTT-CS/SF/Mg(OH)2 nanobiocomposite scaffold, its structural features were characterized using spectral and analytical techniques (FT-IR, EDX, FE-SEM and TG). As well as, given the mechanical tests, it was indicated that the addition of SF and Mg(OH)2 nanoparticles to the CTT-CS hydrogel could improve its compressive strength from 65.42 to 649.56 kPa.

scholarly journals Chemical stability of oil-infused polyethylene

2020 ◽  
pp. 088532822097735
Author(s):  
Fedra P Zaribaf ◽  
Harinderjit S Gill ◽  
Elise C Pegg
Keyword(s):  
Vitamin E ◽  
Chemical Stability ◽  
Antioxidant Properties ◽  
Oxidation Stability ◽  
Thermal Ageing ◽  
Similar Process ◽  
Mechanical Degradation ◽  
Suitable Material ◽  
Thermally Treated

Ultra-high molecular weight polyethylene (UHMWPE) can be made radiopaque for medical imaging applications through the diffusion of an iodised oil-based contrast agent (Lipiodol Ultra Fluid). A similar process is used for Vitamin E incorporated polyethylene which provides antioxidant properties. This study aimed to investigate the critical long-term properties of oil-infused medical polyethylene after 4 weeks of accelerated thermal ageing. Samples treated with an oil (Vitamin E or Lipiodol) had a higher oxidation stability than currently used medical grade polyethylene, indicated by a smaller increase in oxidation index after ageing (Vitamin E + 36%, Lipiodol +40%, Untreated +136%, Thermally treated +164%). The tensile properties of oil treated polyethylene after ageing were significantly higher than the Untreated and Thermally treated controls (p<0.05) indicating less mechanical degradation. There was also no alteration in the percentage crystallinity of oil treated samples after ageing, though the radiopacity of the Lipiodol treated samples reduced by 54% after ageing. The leaching of oil with time was also investigated; the leaching of Lipiodol and Vitamin E followed the same trend and reached a steady state by two weeks. Overall, it can be concluded that the diffusion of an oil-based fluid into polyethylene not only increases the oxidative and chemical stability of polyethylene but also adds additional functionality (e.g. radiopacity) providing a more suitable material for long–term medical applications.

scholarly journals Agent-Based Modeling Demonstrates How Local Chemotactic Behavior Can Shape Biofilm Architecture

mSphere ◽  
2019 ◽  
Vol 4 (3) ◽  
Author(s):  
Emily G. Sweeney ◽  
Andrew Nishida ◽  
Alexandra Weston ◽  
Maria S. Bañuelos ◽  
Kristin Potter ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Three Dimensional ◽  
Structural Features ◽  
Agent Based Modeling ◽  
Emergent Properties ◽  
Cellular Interactions ◽  
Biofilm Growth ◽  
Content Type ◽  
Agent Based ◽  
H Pylori

ABSTRACTBacteria are often found living in aggregated multicellular communities known as biofilms. Biofilms are three-dimensional structures that confer distinct physical and biological properties to the collective of cells living within them. We used agent-based modeling to explore whether local cellular interactions were sufficient to give rise to global structural features of biofilms. Specifically, we asked whether chemorepulsion from a self-produced quorum-sensing molecule, autoinducer-2 (AI-2), was sufficient to recapitulate biofilm growth and cellular organization observed for biofilms ofHelicobacter pylori, a common bacterial resident of human stomachs. To carry out this modeling, we modified an existing platform, Individual-based Dynamics of Microbial Communities Simulator (iDynoMiCS), to incorporate three-dimensional chemotaxis, planktonic cells that could join or leave the biofilm structure, and cellular production of AI-2. We simulated biofilm growth of previously characterizedH. pyloristrains with various AI-2 production and sensing capacities. Using biologically plausible parameters, we were able to recapitulate both the variation in biofilm mass and cellular distributions observed with these strains. Specifically, the strains that were competent to chemotax away from AI-2 produced smaller and more heterogeneously spaced biofilms, whereas the AI-2 chemotaxis-defective strains produced larger and more homogeneously spaced biofilms. The model also provided new insights into the cellular demographics contributing to the biofilm patterning of each strain. Our analysis supports the idea that cellular interactions at small spatial and temporal scales are sufficient to give rise to larger-scale emergent properties of biofilms.IMPORTANCEMost bacteria exist in aggregated, three-dimensional structures called biofilms. Although biofilms play important ecological roles in natural and engineered settings, they can also pose societal problems, for example, when they grow in plumbing systems or on medical implants. Understanding the processes that promote the growth and disassembly of biofilms could lead to better strategies to manage these structures. We had previously shown thatHelicobacter pyloribacteria are repulsed by high concentrations of a self-produced molecule, AI-2, and thatH. pylorimutants deficient in AI-2 sensing form larger and more homogeneously spaced biofilms. Here, we used computer simulations of biofilm formation to show that localH. pyloribehavior of repulsion from high AI-2 could explain the overall architecture ofH. pyloribiofilms. Our findings demonstrate that it is possible to change global biofilm organization by manipulating local cell behaviors, which suggests that simple strategies targeting cells at local scales could be useful for controlling biofilms in industrial and medical settings.

To examine the relationships between supplier development practices and supplier-buyer relationship practices from the supplier’s perspective

2017 ◽  
Vol 24 (5) ◽  
pp. 1309-1336 ◽  
Author(s):  
Sarang Joshi ◽  
Manoj Kharat ◽  
Rakesh Raut ◽  
Sachin Kamble ◽  
Sheetal Kamble
Keyword(s):  
Structural Equation ◽  
Success Factors ◽  
Structural Model ◽  
Manufacturing Firms ◽  
Supplier Development ◽  
Competitive Advantages ◽  
Content Type ◽  
The Relationship ◽  
Relationship Improvement

Purpose The purpose of this paper is to examine the relationships between supplier development practices (SDPs) and supplier-buyer relationship practices from the supplier’s perspective (SBRSP), and seek to understand how specific SDPs may impact a buyer’s operational performance as well as supplier-buyer relationship practices. Design/methodology/approach The authors conducted a survey of 512 respondents from the different manufacturing firms in India and applied structural equation modelling to test a structural model that proposes the impacts of various efforts of SDPs on a buyer’s performance as well as SBRSP. Findings The study concludes that SDPs and SBRSP together improve the relationship between a buyer and supplier, and this improved relationship leads to competitive advantages (CAs) followed by profitability. Results indicate that supplier perspective of buyer-supplier relationship can be improved under the condition of SDPs and SBRSP together. SDPs are driven by productive measure and competitive pressure, whereas customer uncertainty is found to be statistically insignificant. Research limitations/implications The study was carried out in North Maharashtra Industrial Zone of India, where the auto sector and machine/components manufacturing firms have been established for a considerable period of time. Results of the study are limited to manufacturing organizations predominantly focussing on the automobile sector and machine/components manufacturing firms. Practical implications This study provides significant insights into the specific impact of various SDPs and SBRSP for both academics and practitioners. SDPs along with SBRSP practices lead to improvement in the relationship leading to CAs. SBRSP suggests that trust, long-term commitments and the supplier’s perspective are important practices for relationship improvement. Originality/value The current study attempts to identify what are the success factors for the supplier-buyer relationship from the supplier’s perspective and SDPs and how the supplier-buyer relationship can be improved under the condition of SDPs and SBRSP. Hence, the aim is to develop a more thorough understanding of the outcomes of a supplier-buyer relationship improvement from both buyer’s and supplier’s perspective, under the conditions of supplier development to achieve CAs leading to profitability. Furthermore, the study analyses the effect of the improved supplier-buyer relationship for achieving CAs leading to profitability.

scholarly journals Sinabung volcano: how culture shapes community resilience

2019 ◽  
Vol 28 (3) ◽  
pp. 290-303
Author(s):  
Marta Mori ◽  
Ronan McDermott ◽  
Saut Sagala ◽  
Yasmina Wulandari
Keyword(s):  
Structured Interviews ◽  
Content Type ◽  
Aid Dependency ◽  
Relief Operations ◽  
Long Term Impact ◽  
Cultural Experts ◽  
Practical Implications

Purpose The purpose of this paper is to explore how culture, including traditions and social structures, can influence resilience and how culturally sensitive relief operations can put affected people and their context at the core of any interventions. Design/methodology/approach A case study of the Mt Sinabung volcano area in Indonesia was undertaken. As part of the case study, an analysis of interventions was conducted, which was complemented by semi-structured interviews with Karo cultural experts and humanitarian organisations. Findings Culture influences the manner in which the Karo people react to volcano eruptions with varying implications for recovery. In addition, relief organisations which understand people’s actions through a cultural lens have better managed to tailor programs with long-term impact, thereby avoiding aid dependency. Practical implications Practical examples of disaster management activities that adequately account for the beneficiaries’ way of living prior to the eruptions are provided. Aid actors are provided with guidance concerning how to better tailor their activities in line with a cultural lens. Originality/value The study provides empirical grounding for claims concerning the role of culture in planning interventions in Indonesia and other similar contexts.

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